Electron tube for operation with short waves



Dec. 11, 1951 P. GRIVET ELECTRON TUBE FOR OPERATION WITH SHORT WAVES 2SHEETSSHEET 1 Filed Oct. 25, 1947 Arrow/v5 y Dec. 11; 1951 P. GRIVET vELECTRON TUBE FOR OPERATION WITH SHORT WAVES Filed Oct. 25, 1947 2SI'IEETSSI'IEET 2 llllllI/l [III/[111114 Patented Dec. 11 1951 ELECTRONTUBE FOR GPERATION'WITH SHORT WAVES eerie Grivet, are, France, sealantspagnle Generals de Telegraphic Sans Fil, a cor:

poration of France Application October 25, 1947;Se'rialiNo. wearsi InFrance October 24, 1946 Section 1 Public Law 696; August's; 194' Patentexpires October 24, 1966 4 Claims. (Cl:

It is well known'that electronic tubes, whether they have three, four orfive electrodes, become moreand more defective when they work asamplifiers or oscillators, ifthe wave length of the electromagneticoscillations involved becomes small and comes down to an order of valueap pr'oaching one meter. The main difficulties which are met within thatfield of application are the'following:

(19' The spaceseparatingthe'anode from the cathode" is too'lar'ge, andthe electrons take too long-atlme for goingfrom the cathode totheanode;- in other terms the transit time of the electrons becomes tooimportant with reference to the oscillation DBIiOd'.

(2). The passage of the high speed electrons near the control electrodecauses important interchanges of energy with the said electrode,resulting in considerable losses in its circuit. W (3) It is difficultto associate with the classical triodes such circuits as the ones whichoffer a symmetry of revolution, of the ty e of the rhumbatrons or theresonant cavities for instance, which are the only" efficient devices tobe used in conne'ction'withfthe so-called decinieter Waves. My inventionhas for its object topartia'lly solve those difficulties, by combiningthe twofol lowing meanswhich' are separately known: (1) Theuse o'fvolume'resonators, or resonant cavities. H I

(2") A particular disposition of the'electrodes within the tube, thesaid disposition substantially offering the three followingcharacteristics:

(al'lhe' cathode is made out of a relatively thin filamentoriof a planemesh composed or some thin filaments;

(b) The anode'andthe control electrode are set on oneside and the otherof' the plane of filament, or the multiple filaments. Within the tubethus composed, the filament, or filaments are thus disposed between theanode and the control electrode, instead of the control electrodebetween the cathode'and the anode. H p

(c) As the electrons no longer run throughthe control electrode, thelatter may nowfbe' made out of anon-perforated plate a condition whichfacilitates its" cooling and improves its actual work;

A" construction of that sort hasalready been proposed for 'some'longwave applications, or 'for the amplification of direct currents.

My invention provides aconstruction permittlng-operation of tubes atvery'high frequencies. constructionpossesses" advantages" that arederived: from the-elimination of the effectsdue 2 i to the passagenearthe controlelectrode or the electrons intendedfor the anode. The tube0'1 my inventi n is formed about a; symmetry of revolutionaround an axisperpendicular to the plane of the active electrodes so as to: facilitatethe association with those electrodes-of appro pr'iate resonantcavitiesa For a better understandingof my invention, reference will bemade to the following description, which, together with theappendeddrawi'ngs; g ll/e nondimitative instances" ofembodiment, theparticular features appearin' rrom the sai'ddescriptio'n, and-thefigures being, as-should heunderstocdfa part oi the invention.

Figs; 1a and 1b representin'longitudinal and cross sections-a type oft'riode' for shor't waves to which the invention relates;

Fig; 2' represents one iorm of the emitting oath ode whichmay'beemployed in'the' tubes of my invention;- a

Fig. 3'represents', viewed in cros'ssectiomthe triode of Fig.-lsupplemen'ted'by an eleb'tros'tatic screen;

Figs. 4a'and4b'rep're'sent, inlongitudinal and cross sectional views;-respectively, a modifledform' of the screen" shown Fig; 3; and

Fig. s rep'resents a com letely assembledt'ub'e employing my invention;

Figs. 10a and lb represent a" triode" built ac cording: to theinvention; Theanodeis-made'out of a cylindrical-copper row I ,andthecontrol electrode made out' of another rod 2 having" the same diameterand axis as I. In the narrow space left 'betweenthe: ends of the saidtwo'lrods Iarrange theca'thode', preferably composed ofa filament l; orof several elements soldered to two'arc: shaped" members 5 and 6,respectively connected to: leading-in conductors, 3 and 4; sealed-up inthe glass 8 o'f the tube. The fila' ment thus formsa' flat'sheet,extending' ovr' -a width at least -equal to the diameter of the'ro'dsland' 2i Such isthe assembly shown' in lon gitudinal section in Fig?'la, and inFigilU in a transverse:- section, madeby a plane containingthe filament sheetthus perpendicular to th'e aii is common 'to'both -therods l and 2 Experience shows that it is desirable to multiply thenumber of lead=irr wiresin order to: fafoili tate the passage of thehigh frequency currents.

Fig. zshows an insta'nceo'f a particularly eff ficient arrangementembodying-my invention. As in Fig; 1b, Fig; 2 shows asction oi theftubeon af plane containing the so-called filament; the latter is composed of"several strands which diate from a central point 9 and ending theseveral lead-in seals shown at III, II, l2, l3, l4 and I5.

Such a construction lends itself particularly well to the'heating of thefilament, either by direct current or by alternating single phasecurrent if the lead-in wires are parallel-connected by groups of three;it is also possible to heat up the filament by alternating hexaphasecurrents, since the six lead-in wires comprise a star connected system.At point 9 the filaments are all connected together, and they areflattened in such a way that the entire composite filament sheet ofiersthe minimum thickness.

It is often desirable to reduce to the lowest possible value thecapacity between the grid and the plate, and the presence of thefilament may prove insuificient for that purpose. It is possible, inaccordance with my invention, to complete the electrostatic action ofthe filament strands, by adding to it the efiect of a metallic screen aninstance of which is shown in Fig. 3. The said figure corresponds toFig. 1b and bears the same reference numbers; but in addition to thecomponents of the Fig. lb can be seen, in Fig. 3, a screen made out oftwo semi-circles l6 and ll, respectively fixed up on the lead-in wires 3and i. The filament is disposed in an aperture cut out in the twosemi-circular parts [6 and [1.

Figs. 4a and 4b show another embodiment of my invention, in which thescreen I! is made out of one single member and represent one of thepoles of the sheet-filament. The whole of the tube is shown, inlongitudinal section in Fig. 4a, and Fig. 4b represents a transversesection of the same taken on line '44 of Fig. 4a. It can be seen thatthe sheet-filament, comprising three elements for instance, has one ofits extremities carried by a curved member 4 ending in three branches;each one of these elements is stretched between one terminal of a branchand three soldering-points 2i, 22 and 23 on the screen itself. Threeelongated apertures l8, l9 and 20 are opened in the screen, so that thethree elements, located along the axes of these respective apertures,are submitted to the influence of the field created by the anode l andthe control electrode 2. Such a filamentary cathode is formed, in short,of three filaments connected in parallel; the source supplying itsheating current is connected, on one side to the member 4, and on theother side to the screen itself.

Fig. shows, in a longitudinal section, the association of a tube withtwo volume resonators or resonant cavities. The tube proper comprisesthe envelope 8, an anode l, a control electrode 2, and a sheet-filament7 having a given number of lead-in wires such as 3 and 4. The saidlead-in wires are embedded in surface slots made out at the surface ofan annular copper plate 28, and some of them are insulated from theplate by means of a thin sleeve, not shown, so that the heating of thefilament may be effected by connectingto point 28 one of the poles ofthe source. At 25 and 26 can be seen the coaxial lines leading to theanode and control electrode circuits. The passage of the high frequencycurrents towards the cathode is insulated by the mica sheets 24,interposed between the flanges 21 of the concentric casing 29 and thering 28. One at least of those coaxial lines 25 and 26 can slide withrespect to the casing 29 containing the tube. It must be understood thatthe anode j, and the control grid 2 slideat the same time on theirrespective sleeves 30 and 3|. Those adjustments can be effected with allthe precision needed, by means of any accurate device, not shown in thefigure. Two coupling means or loops 32 and 33 are provided, one formedto bring the incoming power to the control grid and the other formed fortaking out the output power needed. By associating these coupling meanswith suitable circuits, the triode may be converted into an amplifier.The positive anode potential is applied at 34. The negative bias or thebiasing resistance for the control electrode 2 can be connected at 35.

Under these conditions, and when the potentials are properly chosen, thetube works efficaciously with very short waves, as readily as would anordinary triode with the conventional long waves.

1 When desiring a very high power efiiciency, one can also, according tothe invention, modify the triode shown in Fig. 5, and convert the sameinto a tetrode or a pentode. One or two supplementary grids are theninserted between the anode l and the filament 1; they are mounted onlead-in seals located in the median plane of the tube, as thoseconnected to the filament strands, and they are introduced into theintervals of the latter. They can also be located in a plane parallel tothe median plane above the filament. It is then possible, with anappropriate construction of the grids and of the filament, to obtain allthe desired effects in the formation of the electron beams, incompliance with the usual technics governing the utilization of thetubes provided with several grids.

It should be understood that the above described devices are only givenas mere instances, and non-limitatively. A number of detailmodifications could be effected in these devices, without deviatingthereby from the scope of the invention, substantially as describedabove.

What I claim is:

1. An electron tube comprising an anode and a control electrode, both ofan elongated stemlike form and disposed on the same axis, and havingtheir terminal faces opposed to each other, an emitting cathode of aplanar form disposed perpendicularly to the axis and between the saidelectrode faces, an envelope surrounding said cathode and the parts ofthe anode and control electrode stems near said cathode, said envelopebeing open at both ends, and two terminal casings surrounding thecentral portion of the tube, and two enclosing end-casings connectedwith said-terminalcasings and comprising appended members adjustablealong the anode and the control electrode, said end-casings forming tworesonant cavities provided with means of taking out the output power onthe anode side, and means for applying the incoming oscillations intothe cavity on the control electrode side.

2. An electron tube as set forth in claim 1 in which the central portionand the end-casings are of cylindrical form.

3. A tube for operation on decimeter waves, comprising an anode and acontrol electrode, both in the form of solid stems, disposed along thesame axis with their end faces facing each other, an emitting cathode ofa flat form, disposed between the said faces and in a planeperpendicular to this axis, a vacuum-tight envelope of insulatingmaterial surrounding the said oathode and the ends of the stems of theother electrodes and forming a unit, a metal casing in the form of acylinder surrounding the said unit and having as its axis that of thesaid electrodes, this casing consisting of a fixed central portionsupporting the said vacuum-tight envelope and open at its two ends andof two closed end portions in the form of end pots sliding frictionallyon this central portion, and coupling means lodged in the said end pots.

4. A tube for operation on decimeter waves, comprising an anode and acontrol electrode, both in the form of solid cylindrical stems disposedalong the same axis with their end faces facing each other, an emittingcathode forming a flat emitting surface, disposed between the said facesand in a plane perpendicular to this axis, a vacuum-tight envelope ofinsulating material surrounding the said cathode and the ends of thestems of the said electrodes, on the side of the cathode, said stemsextending beyond the said envelope, a cylindrical metal collarsurrounding the said envelope and supporting it and having as its axisthat of the electrodes said cathode dividin said envelope into twoparts, two closed metal casings in the form of pots of a cylindricalform of revolution about the said axis and closing the said metal collarat its two ends to form two resonant cavities, their diameters beingsuch that these casings can be frictionally displaced on the saidcollar, said casings presenting recessed appendices of a tubular formfrictionally surrounding the external ends of the said stems of theelectrodes, and coupling means lodged in the said cavities.

PIERRE GRIVET.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

